Typical of the type of machines which may use electrical contacts and devices are electrostatographic printing machines. In electrostatographic printing apparatus commonly used today, a photoconductive insulating member is typically charged to a uniform potential and thereafter exposed to a light image of an original document to be reproduced. The exposure discharges the photoconductive insulating surface in exposed or background areas and creates an electrostatic latent image on the member which corresponds to the image contained within the original document. Alternatively, a light beam may be modulated and used to selectively discharge portions of the charged photoconductive surface to record the desired information thereon. Typically, such a system employs a laser beam. Subsequently, the electrostatic latent image on the photoconductive insulating surface is made visible by developing the image with developer powder referred to in the art as toner. Most development systems employ developer which comprises both charged carrier particles and charged toner particles which triboelectrically adhere to the carrier particles. During development the toner particles are attracted from the carrier particles by the charged pattern of the image areas of the photoconductive insulating area to form a powder image on the photoconductive area. This toner image may be subsequently transferred to a support surface such as copy paper to which it may be permanently affixed by heating or by the application of pressure to form the desired copy.
In commercial applications of such printing machines it is necessary to distribute electrical power and/or logic signals to various sites within the machines. Traditionally, this has required conventional wires and wiring harnesses in each machine to distribute power and logic signals to the various functional elements in an automated machine. In such distribution systems, it is necessary to provide electrical connectors between the wires and components. In addition, it is necessary to provide sensors and switches, for example, to sense the location of copy sheets, documents, etc. Similarly, other electrical devices such as interlocks, and the like are provided to enable or disable a function. These electrical devices are usually low power operating at electronic signal potentials up to 5 volts and at currents in the milliamp regime. Further, many commercial applications employ electrical contact components and related devices that require use in higher power applications employing currents in the regime of 1-100 amps and voltages greater than 5 volts. The present invention is not limited to signal level currents or low potential applications and includes applications in higher power regimes requiring greater current carrying capacity.
Conventional laser processing of electrical components to produce, for example, a distributed filament contact component can result in a clean cut in the limited sense that all of the fibers are uniformly cut and that the length of all fibers projecting from the matrix are approximately the same, or alternatively, that all of the fibers are uniformly cut, are not jagged, and, all of the tips are on an equal plane with the matrix. However, conventional laser processing has been discovered to result in the generation of substantial chemical residue which appears as a contaminant on the electrical components which must be removed in a post laser processing procedure, thereby increasing the complexity and cost of the electrical component fabrication process. This residue is observed to exist in several different forms such as: a carbonaceous, solid powdery substance, (referred to herein as char), a tacky, tar-like, or glue-like resinous film (referred to herein as tacky film), and a rigid, hard crusting layer (referred to as crust). The residue has been observed to exist on the fiber tips, between the fibers, between the tip ends and the matrix, and, on the external surfaces of the composite for a significant distance, for example, 2 to 4 mm away from the cut region. We have observed problems associated directly with each of these forms of contaminant if they are not removed from the contact either during or after laser processing. For example, the tacky film is particularly problematic when it deposits upon the outer surfaces of the parts because it causes the parts to adhere together when stacked in magazine feeders for auto-feeding apparatus of an automated manufacturing process. The presence of tacky films necessitates that the parts are not permitted to contact other parts or nearby surfaces after laser processing, otherwise the parts will stick together, in effect, preventing the parts from being separated from one another without damage or breakage. Thus, in the absence of this invention, a complex and costly chemical removal of the tacky film at the point in the overall process immediately after laser processing would be required to enable efficient, automated handling of the parts. Likewise, the presence of even very small amounts of char or crust is found to contaminant the contact surface and adversely affect the electrical or mechanical functions of the resultant device. Thus, there is a need, which the present invention addresses, for new electrical component compositions where laser processing of the electrical component results in a clean cut in the broader sense that the generation of unwanted residue is eliminated or minimized and that the tips of the fibers regardless of whether they are on an equal plane with the matrix or extend for a distance from the matrix, are not covered with matrix resin or residue from the thermal decomposition of the resin.
Conventional electrical components are disclosed in Swift et aL, U.S. Pat. No. 5,599,615; Orlowski et al., U.S. Pat. No. 5,270,106; Swift et al., U.S. Pat. No. 5,250,756; and Swift et al., U.S. Pat. No. 5,139,862. In addition, Bristowe et al., U.S. Pat. No. 4,506,055, discloses carboxy modified vinyl ester urethane resins.
Swift et al., U.S. application. Ser. No. 08/868,390 (Attorney Docket No. D/97082), filed Jul. 3, 1997, now U.S. Pat. No. 5,843,567 discloses an electrical component containing magnetic particles, where there is described on page 13 an electrical component including Amoco T300.TM. carbon fiber sized with Amoco UC-309.TM. resin, MODAR 826HT.TM. as the matrix available from ICI, plus a small amount of a suitable lubricant such as polyethylene wax and a curing agent such as Noury PERCADOX 16N.TM..
There are also a number of manufacturer publications regarding MODAR.TM. resins and their uses (24 pages).